(CNN) -- RVs are gaining traction. The recreation vehicle market is rebounding after the economy's plunge drove previously growing sales off a cliff.

Now 8.3 million American families own RVs, according to the Recreation Vehicle Industry Association. If you're thinking about joining this crowd, consider carefully. Buying one is a big investment. RVs can cost more than many people pay for their homes, and gas prices right now mean the cost of life on the open road is on the rise.

RVs were once thought to be the toys of older drivers. But the industry association now says most RVs are owned by drivers from 35 to 54 years old and the largest percentage-gain in ownership is for people 35 years and younger.

Whatever their age, owners say it's all about freedom. RV-ers go where and when they want, bypass airport security, avoid luggage fees and restrictions, tow the family car, and have room for kids and pets.

For RV enthusiasts Ruth and Bud Spezio of Oakhurst, New Jersey, there's also the comfort factor: "We sleep in our own bed, on our own sheets, use our own towels, eat on our own dishes," said Bud Spezio. The thought of staying in hotel rooms appalls them.

Diane and Charlie Wathke of Greenwood, Wisconsin sold their house, their furniture and most of their clothes so that they could live full-time in their 40-foot motor home.

Aside from the freedom and the lifestyle, RV-ers like other RV-ers. Eloyce Lyster, of Naples, Florida, enjoys spending time traveling in her RV. The people she's met and the friends she's made are her favorite part of the RV experience.

So, is an RV right for you? Here are four factors to consider:

Cost: RVs come in all sizes, motorized and towable -- from simple truck campers and pop-ups to gigantic motor homes that look like Greyhound buses on steroids. They range from class A the largest), class B (the smallest) and class C (medium sized) to fifth-wheel travel trailers (pulled by hefty pickups), and more.

Trailers or pop-ups cost from $4,000 to $6,000. A 27-foot class C runs from $48,000 to $140,000. Depending on the size and options, a large class A can set you back $400,000, and truly deluxe options can run into the millions. The good news is that buyers often qualify for competitive interest rates. RV loans extend from 10 to 15 years, with 10% to 20% down payments. And if the vehicle is deemed a first or second home, rates may be deductible on income taxes as "mortgage" interest.

Upkeep: The bigger the RV, the fewer miles-per-gallon it gets. That's a major consideration as gasoline prices head through the roof. Repairs, when needed, may take longer and cost much more than repairs on cars or trucks. Changing a flat tire is virtually impossible. So owners buy roadside assistance plans for emergencies. National Motor Club charges $129.50 per year and Good Sam charges $109.

Getting around: Unlike the family sedan, the RV ride can be bumpy and uncomfortable, especially for those sitting at the dining table. But when you need to stop, there are some 16,000 public and private campgrounds. Some are reasonable -- $25.00 per night for a full hookup -- but others can be very costly. In peak season, campsites can be crowded and noisy. These vehicles dwarf even the biggest SUV, and backing into RV campsite locations can be like putting a tractor-trailer in reverse.

Experience: RV aficionados say the reason they love the lifestyle boils down to this: Vacations in their behemoths are better and easier than, say, flying hundreds of miles to a distant airport, renting a car, paying for a hotel, and eating out three times a day. RV-ers have their own transportation, their own lodging, and a place to prepare all meals. The 2008 PKF Vacation Cost comparison study shows that a family of four can save 27% to 61% on vacation costs traveling in an RV, after factoring in ownership costs and fuel, according to RV News.

If you're not sure, you can rent an RV to see if you like it. Check "RV rentals" online.

Spend a week or two in a recreational vehicle. Hook up at campsites, pump out the sewage tank, monitor the cost of gas, enjoy the view from the large picture windows, see how cramped the toilet and shower are, cook your own meals and try backing into a small campsite slip. Then you'll know firsthand the joys and challenges of owning a big "boat".

George Bauer works at CNN and is also the creator and host of "The Seasoned Traveler," which airs on U.S. public television stations and Travel Channel International. He has rented a class C RV for three vacations.